Mature size & growth rate

How big does Merrill's Wax Plant (Hoya merrillii) get?

Also called Merrill's wax plant, Merrill's hoya, Philippine wax plant.

More about merrill's wax plant

About Merrill's Wax Plant

Hoya merrillii · also called Merrill's wax plant, Merrill's hoya · tropical

Hoya merrillii is a rare epiphytic vine native to the Philippines, first discovered in humid lowland forests on Mindoro Island, and named in honour of American botanist Elmer Drew Merrill who extensively documented Philippine flora. It is prized for its compact umbels of up to 25 small, star-shaped, golden-yellow flowers with red-orange centres that emit a sweet, honey-and-caramel fragrance most intense in the evenings. The most important care point is to provide warm temperatures with high humidity and avoid cold draughts, as it cannot tolerate temperatures below 15°C for any length of time. The ASPCA lists the Hoya genus as non-toxic to cats and dogs.

Mature size: Typically 1–2 m as an indoor container plant; can grow larger in warm greenhouse conditions.

Indoor size vs how big it gets in the wild

Merrill's Wax Plant does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims. Indoors and in a pot, expect typically 1–2 m as an indoor container plant. In the ground with no restriction it is a completely different plant — can grow larger in warm greenhouse conditions. — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Growth rate and years to mature

Merrill's Wax Plant is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: feed monthly in spring and summer with a half-strength balanced liquid fertiliser; switching to a low-nitrogen, high-potassium feed in late summer can help promote flowering.

Want this turned into the right next pot at the right moment? The pot size calculator and the merrill's wax plant repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast merrill's wax plant grows.

How to keep merrill's wax plant smaller

You are not stuck with the maximum size. For merrill's wax plant specifically, these are the levers, in order of impact:

Trim the longest vines back to the length you want — merrill's wax plant takes hard cutting well and bushes out from the cut.
Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser.
The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants.
A trim once or twice a season is usually enough to hold its length.

The keep-it-smaller method, step by step

Decide the length you want. Pick the point each vine of merrill's wax plant should stop — you can be aggressive; it regrows readily.
Cut just above a node. Snip about 0.5 cm above a leaf node so the stem branches there instead of dying back.
Root the cuttings. Drop the trimmed pieces in water or mix — they root in 2-4 weeks and can fill the same pot for a bushier look.
Repeat as it runs. Re-trim whenever it overshoots; regular light pruning keeps it both smaller and fuller.

How to grow merrill's wax plant bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for merrill's wax plant the accelerators are:

Good light plus a moss pole or trellis triggers the longest, fastest, largest-leaved growth.
Give it something to climb — many vines grow far faster and bigger up a support than trailing.
Feed through spring and summer and keep it consistently watered while it is actively running.

Light is almost always the ceiling. The merrill's wax plant light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When merrill's wax plant outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for merrill's wax plant:

Vines pooling on the floor or wrapping past where you want them — purely a trimming cue, not a repot one.
Bare, leggy stems with leaves only at the tips (usually a light problem, not a size one).
A tangled mass that has outrun its support and needs cutting back and re-training.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the merrill's wax plant repotting guide. If you want more of this plant instead of a bigger one, the merrill's wax plant propagation guide turns prunings into new plants.

Merrill's Wax Plant size — frequently asked questions

How big does merrill's wax plant get?

Merrill's Wax Plant reaches typically 1–2 m as an indoor container plant when grown indoors, and far larger where it grows unrestricted (can grow larger in warm greenhouse conditions.). Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Is merrill's wax plant slow or fast growing?

Merrill's Wax Plant is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Merrill's Wax Plant does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims.

How long does merrill's wax plant take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep merrill's wax plant smaller?

Trim the longest vines back to the length you want — merrill's wax plant takes hard cutting well and bushes out from the cut. Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser. The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants. A trim once or twice a season is usually enough to hold its length.

How can I make merrill's wax plant grow bigger or faster?

Good light plus a moss pole or trellis triggers the longest, fastest, largest-leaved growth. Give it something to climb — many vines grow far faster and bigger up a support than trailing. Feed through spring and summer and keep it consistently watered while it is actively running.